The method and apparatus for gas particle formation according to the invention can be used in any application requiring efficient aeration of liquid media such as, for example, aeration/oxygenation for biological waste liquid purification using aerobic micro-organisms, liquid/slurry preaeration and/or combined shear flocculation, liquid gasification and suspension of minerals or coal enrichment. The following description will be given with particular reference to gas particle formation and dispersion in a liquid/slurry in mineral flotation apparatus, however it will be appreciated that the inventive method and apparatus has much wider applications.
Froth flotation is a process used for concentrating values from low-grade ores. After/during fine grinding the ore is mixed with water to form a slurry. Chemicals are added to the slurry to preferentially develop differences in surface characteristics between the various mineral species present. The slurry is then copiously aerated and the preferred (hydrophobic) mineral species cling to bubbles and float as a mineralised froth which is removed for further processing.
It is well established that a key factor in the performance of the flotation technique is the size, volume and distribution of gas particles or air bubbles that can be dispersed into the slurry. The present invention was developed with a view to providing a method and apparatus for gas particle formation in which the desired size of gas particles can be readily controlled and a relatively uniform distribution of gas particles can be achieved irrespective of the gas flow rates required by the process. Several further improvements to flotation apparatus are also described.